He had been working as a contractor and "research scholar" at NASA on "high-tech imaging technology".

One US congressman said that if his work had been leaked it "potentially could be a direct threat to our country".

Representative Frank Wolf added that "the Chinese have the most comprehensive spying program in Washington that has ever been".

Wolf alleges that NASA are not taking the threat seriously, though the situation is complicated because Wolf is chairman of the House Appropriations subcommittee that funds the agency.

Jiang admitted he had a mobile phone, a memory stick, an external hard drive and a laptop when he tried to leave the States, the FBI said.

Special Agent Rhonda A. Squizzero added:"However, during the search, other media items were located that Jiang did not reveal. Such items found include an additional laptop, an old hard drive and a SIM card."

It is not known, or has not been revealed, what data was on the devices.

NASA said it was reviewing "a potential security breach" but did not elaborate.

"The agency takes any allegation of a security violation very seriously," it said.

The US has a law called ITAR (International Traffic in Arms Regulations) which restricts the dissemination of weapon and dual-use technologies (items with both civilian and military uses.)

It goes so far that even images of parts of the old Saturn V, or new Falcon 9, rockets are restricted. Even certain computer hsrdware is on the list and cannot be sold or shipped overseas..Ditto some industrial gear.

The problem is that many academics are sloppy, or just ignore, ITAR when it comes to sharing info with visiting foreign nationals whose countries or organizations are on the restricted list. Many cite "academic freedom" or other such nonsesne (as in this case.)

The problem in this case is that many of the techs this guy was given access to at JPL were dual-use and could be perverted into precision weaponry. His access to many of these hardware & software techs makes no sense because his specialty was image analysis, especially edge detection in probe imagery.

In spite of this he was allowed to take a NASA laptop with restricted info back to China on a previous trip, and on this trip he tried to export storage devices etc. that he hadn't declared when auestioned.

The whole affair stinks not only because of the security violations, but because of the attitude of his superiors and the cover-up.